Francis l



E. L. FREAS.

THERMOMETER.

APPLICATION FILED AUG. s. 1918,

Patntedsept. 23, 1919.

Imwim Francis Ljraas,

. with the bulb PATENT orrio.

FRANCIS L. FREAS, 0F GONSHOHOCK'EN, PENNSYLVANIA.

THERMOMETER.

Specification of Letters Patent. t t g m, 23, 111919,

Application filed August 5, 1918. Serial No. 248,247.

To all whom it may concern A Be it known that I, FRANCIS L. Films, of

i ionshohocken, in the county of Montgomand State of Pennsylvania, have inventcertain new and useful Improvements in 'lhermometers, whereof the following is a .specification, reference being had to the accompanying drawings.

My improvements relate to the so-called 19 insulated thermometers, and may be embodied in a device intended to float in upright position when immersed in liquids, but their use is not restricted to such floating devices. In the accompanying drawings, Figure I represents an exterior view, in front elevation, of a thermometer embodying my invention; Fig. II," a partial axial section through the lower portion of the thermometer and casing; Fig. III, an interrupted 20 longitudinal section on a plane at right angles to that ofFig. II; and Fig. IV a crosssection on the line IV-IV of Fig. III.

The device comprises the following main elements:

80 rounded end socket 3, whose section may be p insidered as substantially hemispherical,

d whose inner surface should be true and symmetrical. The casing is closed at the upper extremity as shown at 4, and is provided with an eye 5.

The thermometer element is of the usual form, comprising a capillary-tube 6, a substantially spherical bulb 7, the exterior surface of the lower half of the bulb being 40 formed in substantial symmetry with the internal surface of the socket 3, and being of such dimensions that said lower half of the bulb may fit snugly within the socket. The

capillary'tube is bent at an angle a short distance from the bulb, as indicated at 8, and

the stem is thus inclined toward the inner surface of the casing, preferably coming into 7 contact therewith near the upper extremity,

as shownat 9. I v

The thermometer element having been arranged in the position shown the fi es, seated within the 's'oc et 3, I fill the interspace atthe lower portion of the casing with granular thermally con- 155 ducting materiah preferably very fine shot, as indicated Lt-10.; .Where, as in the instance 'The'external casing or insulating member shown in the drawings, the lower portion of the casing is tapered, the zone or region occupied by the shot is preferably made to terminate a short distance below the upper extremity of the tapered portion. The shot or granular material is carefully packed, or shaken into a position of com plete rest, so that the body of material as a whole shall be practically stable under the conditions of use, and the quantity of material may be determined with reference to the desired buoyancy of the structure, as a whole, in a liquid of given density.

When the bulk has been thus inserted and the body of the granular material properly packed in'sta'ble condition, I apply a belt 11 of material whichis capable of being introduced in a plastic condition, but which will harden, and remain strongly adhesive to the glass of the casing and of the thermometer element. If the'material of the belt 1'1 is of such character as to be rendered plastic by heat, (such assealing wax, for instance) it should have a softening-point not sub-. stantially lower than the highest temperature to which the thermometer would be subjected under normal conditions of use.

When the belt of adhesive material has been applied and hardened in adhesive relation to the respective glass surfaces, the thermometer element will be retained with great stability in position with its upper end preferably in light contact withthe surface of the casing, by the combined effect of the bulb fitting within the socket 3, the extended sup port afforded by the body of granular material 10, and the belt of adhesive material 11. In order,'however, further to enhance the stability of the capillary tube particu-- larly at its upper portion which is remote from the embedded bulb and lower portion of the stem, I-employ a scale element, formed preferably of paper having .a substantial amount of stifiness, which is disposed in the form of a cylinder 14: fitting closely within the bore of the casing, and which is inserted r -T e irgaduations indicating tfiefiivisions erting tension against the tu e throughout arranged in longitudinal bands on each side of the graduations as shown. When the paper cylinder has been inserted to the proper depth (which is, of course, determined by the known relation of the expansible material within the bulb and capillary tube to the indicated scale temperatures), the paper cylinder is preferably secured in position by adhesive material applied at its upper region, so as to be held permanently in place, such securing being aided by the frictional contact between the paper cylinder and the interior surface of the casing, due to the pressure occasioned by forcing the paper cylinder behind the capillary tube.

u sequently, of course, the upper end of the casing is closed, as shown.

I am aware that it is not new to form insulated thermometers by making the glass of the thermometer bulb integral with the glass of the lower extremity of the casing, but such devices are diflicult and expensive to make, and are obviously structurally different from the device embodying my invention.

- I am also aware that the use of shot for fined to the lower portion thereof and inv contact with the lower portion of said ther-- mometer element; and a belt of adhesive material above said packing securing the same in place in said casing.

2. The combination of; a closed cylindrical casing havin at its lower extremity, a socket with a su stantially symmetrical internal surface; a thermometer element arranged wit-hin said casing, having a bulb adapted to fit within the socket of the casing, and having a capillary tube bent at its lower portion; a substantially stable body of granular thermally conducting material, arranged in contact with the lower portion of said thermometer element; a belt of adhesive material arranged in contact with the upper surface of said granular body and secured to 1 the interior surface of the casing and eX- terior surface of the capillary tube; and a scale memberarranged in pro er relation to the thermometer element, su stantially as set forth.

3. The combination of; a closed cylindrical casing having, at its lower extremity, a socket w1th a substantially symmetrical internal surface; a thermometer element arranged within said casing, having a bulb adapted to fit within the socket of the casing and having a capillary tube bent at its lower portion; a substantially stable body of granular thermally conducting material, arran ed in contact with the lower portion of sai thermometer element; a belt of adhesive material arranged in contact with the upper surface of said granular body and secured to the interior surface of the casing and exterior surface of the capillary tube; and a scale member of relatively stiff pliable. material, disposed in cylindrical form, and having a longitudinal trough adapted to receive the capillary tube, in tensional relation thereto, substantiall as set forth.

In testimony whereo I have hereunto signed my name, at Philadelphia, Pennsylvania, this first day of August 1918.

FRANCIS t. FREAS.

Witnesses:

JAMES H. BELL, Hmn W. HALL. 

